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jfs: fix null ptr deref in dtInsertEntry

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[syzbot reported]
general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 PID: 5061 Comm: syz-executor404 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:dtInsertEntry+0xd0c/0x1780 fs/jfs/jfs_dtree.c:3713
...
[Analyze]
In dtInsertEntry(), when the pointer h has the same value as p, after writing
name in UniStrncpy_to_le(), p->header.flag will be cleared. This will cause the
previously true judgment "p->header.flag & BT-LEAF" to change to no after writing
the name operation, this leads to entering an incorrect branch and accessing the
uninitialized object ih when judging this condition for the second time.

[Fix]
After got the page, check freelist first, if freelist == 0 then exit dtInsert()
and return -EINVAL.

Reported-by: syzbot+bba84aef3a26fb93deb9@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
This commit is contained in:
Edward Adam Davis 2024-04-11 20:05:28 +08:00 committed by Dave Kleikamp
parent ee6817e72d
commit ce6dede912
1 changed files with 2 additions and 0 deletions
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2
fs/jfs/jfs_dtree.c
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@ -834,6 +834,8 @@ int dtInsert(tid_t tid, struct inode *ip,
* the full page.
*/
DT_GETSEARCH(ip, btstack->top, bn, mp, p, index);
if (p->header.freelist == 0)
return -EINVAL;
/*
* insert entry for new key